| 摘要 |
PURPOSE:To improve the durability of a brake band and reduce drag torque in a wheel hub for a four-wheel driving car by operating a brake shoe that engages, in hole-protrusion shape, with almost a C-shaped plate spring using its expansion and contraction. CONSTITUTION:Brake shoes 22B are engaged with a almost C-shaped plate spring 22A with pawls 22a1 which are bent inward at the both ends thereof while protrusions 22b are engaged with holes 22a2 perforated in the plate spring 22A. Thus, the brake shoes 22B are contacted with or separated from the inner surface of the brake drum 20 according to the expansion and contraction of the plate spring 22A. In such structure, since there is no brake shoe mounting hole in the intermediate section of the plate spring 22A, stress concentration can be prevented and durability can be improved even when the plate spring is contracted by the engagement of a slide ring protrusion 18a with the pawl 22a1. Besides, since the brake shoe B with which the protrusion 18a engages is separated fully from the drum 20, drag torque can be reduced. |
